The U.S. Food and Drug Administration (FDA) has declined to review Moderna's application for its new messenger RNA (mRNA) influenza vaccine. This decision marks a significant step for the development of mRNA-based vaccines beyond COVID-19 and raises questions about the regulatory process and clinical trial design. The FDA states its refusal is due to the clinical trial's design, specifically the comparator vaccine used, while Moderna asserts its trial followed agreed-upon protocols and regulatory guidance.
Background on Moderna's mRNA Flu Vaccine
Moderna, a company known for its mRNA COVID-19 vaccine, developed a new influenza vaccine utilizing the same Nobel Prize-winning technology. This mRNA approach theoretically allows for quicker updates to vaccine strains to match circulating viruses. Moderna had previously announced it would not invest in new late-stage vaccine trials due to growing opposition to immunizations, though this decision appears separate from the FDA's current refusal. The company had sought approval for this flu vaccine in Europe, Australia, and Canada.
Read More: King Charles Talks About Cancer and His Work
The core issue revolves around Moderna's Phase 3 study design and the vaccine it used for comparison.
The Dispute Over Clinical Trial Design
The FDA's primary reason for declining to review Moderna's application centers on the clinical trial design. Specifically, the dispute involves what Moderna compared its mRNA flu vaccine against during its Phase 3 study.
FDA's Stance: The FDA has indicated that Moderna's chosen comparator vaccine was not the best standard of care at the time of the study. Communications from the FDA's Center for Biologics Evaluation and Research (CBER) suggested that Moderna's vaccine should have been compared against a control shot specifically designed for older individuals, who are more vulnerable to flu complications. The agency stated that the trial "put patients at risk" by not using the best available standard of care.
Moderna's Counterargument: Moderna maintains that the trial was conducted as regulators had discussed and agreed upon. The company argues that FDA rules and guidance do not strictly mandate the use of the most advanced or highest-dose vaccine as a comparator in clinical studies. Moderna has presented a timeline of its communications with the FDA, indicating the agency asked for additional data comparing its flu shot against existing vaccines for older individuals.
Read More: US Prices Rise Slower in Early 2026
The FDA contends the comparator vaccine used in Moderna's trial was not the best standard of care, a point Moderna disputes, stating they followed agreed-upon protocols.
Communication and Regulatory History
The FDA and Moderna have been in communication regarding this mRNA flu vaccine for approximately two years, since Moderna submitted its Phase 3 data. This period of back-and-forth is typical in the regulatory process for new vaccines.
"Refusal to File": It is noted as rare for the FDA to refuse to file an application for a new vaccine, a process that usually involves extensive discussions between companies and regulatory staff over months or years.
Moderna's Response: Moderna has requested an urgent meeting with the FDA to discuss the matter further. The company has also proceeded with seeking approval for the vaccine in other regions, including Europe, Australia, and Canada.
Read More: More Americans Sell Plasma to Pay Bills
The FDA's refusal to file is described as rare, and Moderna has requested an urgent meeting while pursuing approvals in other countries.
Broader Implications for mRNA Vaccines
The FDA's decision has potential implications for the broader development and adoption of mRNA technology in vaccines beyond COVID-19.
Technological Advantage: mRNA vaccines offer the theoretical advantage of faster strain updates, which could be crucial for rapidly adapting flu vaccines to new viral strains.
Regulatory Scrutiny: The situation highlights the ongoing regulatory scrutiny of new vaccine technologies and the critical importance of rigorous clinical trial design that meets regulatory expectations.
Public Perception: One article notes comments suggesting that some public health figures, like Robert F. Kennedy Jr., are taking a "harder line" on mRNA shots, although the FDA stated it does not comment on regulatory communications with individual sponsors and did not cite safety or efficacy concerns with Moderna's vaccine itself.
Read More: Vulcan Rocket Reaches Space Despite Booster Problem
This regulatory outcome may influence future mRNA vaccine development and public perception, despite the technology's potential for rapid adaptation.
Conclusion and Next Steps
The FDA's refusal to review Moderna's mRNA influenza vaccine application is based on a disagreement over the adequacy of the clinical trial's comparator vaccine. While Moderna believes it followed regulatory discussions and guidance, the FDA maintains the chosen comparator did not represent the best standard of care.
Moderna has applied for approval in other countries and has requested an urgent meeting with the FDA to resolve the issue. The outcome of these discussions will be significant for the future of mRNA vaccine development for influenza and potentially other infectious diseases. The FDA has not identified specific safety or efficacy issues with the vaccine itself, but rather with the design of the pivotal trial submitted for review.
Sources Used:
The Hindu: https://www.thehindu.com/sci-tech/health/why-did-the-us-fda-decline-to-review-the-new-mrna-influenza-vaccine/article70628014.ece
Context: This article provides an overview of the FDA's refusal, Moderna's position, and the technical aspects of the trial design.
USA Today: https://www.usatoday.com/story/news/health/2026/02/10/moderna-fda-mrna-flu-vaccine-review/88613885007/
Context: This article reports on Moderna's announcement of the FDA's refusal and touches on the company's broader vaccine trial investment strategy.
NBC News: https://www.nbcnews.com/health/health-news/fda-defends-decision-not-review-modernas-mrna-flu-shot-rcna258642
Context: This article focuses on the FDA defending its decision and elaborates on the core dispute regarding the clinical trial's comparator vaccine.
CBC News: https://www.cbc.ca/news/health/fda-refuses-moderna-vaccine-9.7084375
Context: This article details the FDA's refusal and notes the rarity of such an event, alongside Moderna's international applications and requests for meetings.
TIME: https://time.com/7377817/moderna-new-flu-shot-fda-review/
Context: This article provides an overview of the FDA's decision, the timeline of communications, and the specific points of contention regarding the comparator vaccine for older populations.
CNBC: https://www.cnbc.com/2026/02/10/moderna-fda-flu-shot.html
Context: This article reports on Moderna's announcement and highlights Moderna's dispute of the FDA's reasoning regarding trial design requirements.
Read More: Seaweed: Good for Your Health and Body
